1. Technical Field
The invention relates to straps for securing cargo, particularly to tighteners for tightening the straps.
2. Related Art
Cargo on a flatbed truck must be secured by straps for transportation, and the straps must be tightened by ratchet tighteners. A ratchet strap tightener can unidirectionally and laborsavingly strain a strap and prevent it from loosing.
A typically conventional ratchet strap tightener as shown in U.S. Pat. No. 6,457,701 is a swingably vee structure composed of a base frame 11 and a handling frame 21. The base frame 11 and handling frame are separately provided with pivot holes for being penetrated by a pivot 23. Two ends of the pivot 23 are separately ringed with two ratchet wheels 22 so that the pivot 23 can synchronously rotate with the ratchet wheels 22. As can be seen in the drawings of '701, the pivot 23 is in direct contact with edges of the pivot holes. The pivot 23 is connectedly rotated by wrenching the handling frame 21 for winding and straining the strap 100. After the strap 100 has been strained, the tension of the strap 100 will be exerted on the pivot 23 and finally bear against the edges of the pivot holes. However, the base frame 11 is composed of metal plates, so its strength is limited. The pivot holes tend to be deformed by pressure exerted by the pivot 23 in long-term use. Once the pivot holes are deformed, the pivot 23 will be stuck in the pivot holes and hard to or even unable to rotate. As a result, the strap 100 cannot be released. This is a primary problem of the conventional strap tighteners.